Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: student101 on January 14, 2005, 10:56:50 PM
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I know that a double bond has the two atoms closer to each other than a single bond. I have to build an acetylsalicylic acid model for chemistry and would like to know:
- Is there a ration between the lengths of C-C bonds to C=C bonds?
- Are C-H bonds closer together than C-C bonds?
- Are C=O bonds closer together than C=C bonds?
- If i'm building a model out of styrofoam balls and sticks, would C and O atoms be essentially the same size (i know O has a smaller atomic radius than C, but is it significant) --> i intend on using a colour code (black - C, red - O)
The first question is my top priority. Any help would make a huge difference - thanx!
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you can always refer to the "CRC handbook for chemistry and physics" for the bond length (in angstrom).
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Is there any way i could get this info online? (It's kinda last minute)
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C=O vs C=C bond length
you also have to take into consdieration the size of each atom that constitutes the double bond
i got the 84th edition CRC book, but haven't used it yet lol ;D
i got it as a prize in chemistry i guess :)
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the (double bond)/(single bond) ratio depends on so many factors that you don't even know exists yet. The ratio (134)/(154) should work out for you just fine.
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There are lists of bond lengths & energies here:
http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html
http://chemviz.ncsa.uiuc.edu/content/doc-resources-bond.html
Note that in acetyl salicylic acid all of the carbon-carbon bonds in the 6-membered ring will actually be the same length (somewhere between the length of a C-C single bond and a C-C double bond). This is because the ring is said to be "aromatic." Essentially, the double bonds can shift around the ring to make two equivalent "resonance" structures. In reality, the molecule is a mixture of the two resonance forms. The formal resonance structures represent the extreme forms.
Also, I don't think that the difference in size between oxygen and carbon will make much of a difference in your model. The difference in atomic radius between C and O is about 8 pm (http://www.iumsc.indiana.edu/radii.html)